If a translatable page A/B is a subpage of a page A, and the page A is being moved with its subpages to C, A/B gets moved to C/B but its translations A/B/en, A/B/foo, A/B/bar as well as unit pages Translations:A/B/1/en, Translations:A/B/2/bar and so on do not get moved. They can't be moved after it manually as well. So the translatable page now C/B needs to be moved back to A/B and then moved to C/B along with its satelites.
Thus when moving pages like A pages like A/B should either be moved the same way as when you move them directly or not moved at all.
(I'm sorry for kinda messy desc, didn't find right words to explain it without "variables")